This new research project builds on previous research on non-native invasive species, such as glossy buckthorn. UNH researchers have planted an orchard of the fast-growing shrub at UNH’s Kingman Farm to determine the life history characteristics of invasive glossy buckthorn under controlled conditions, free from competition with other plants, and free from variation in other environmental factors such as soil or micro-climate. Credit: UNH

Invasive, non-native plants have a significant detrimental impact on Granite State forests. A new research project funded by the NH Agricultural Experiment Station at the University of New Hampshire will assess the status and distribution of invasive plant species throughout New Hampshire that pose the greatest threat to the state’s forest systems, with the goal to help foresters and landowners minimize the risk of invasive plants to the state’s economically important forests.

The research project “Invasive Plant Impacts on New Hampshire Forest Ecosystem Services” is led by John Gunn, research assistant professor of forest management, and a researcher with the NH Agricultural Experiment Station. Gunn also has an appointment at UNH Cooperative Extension.

“The health of New Hampshire’s forests faces many threats from non-native and invasive plants introduced over the last two centuries. These non-native species now make up at least 30 percent by species of all plants in New England. Several species already are widespread throughout the state, such as burning bush, glossy buckthorn, multiflora rose, and Japanese barberry. Warming temperatures in this century are likely to favor conditions for the expansion of existing populations of invasive plant species and facilitate newcomers to the state’s borders,” Gunn said.

According to Gunn, invasive non-native plants lead to significant financial and ecological damage to forest systems and are likely to increase in scale and severity under a warming New Hampshire climate. Ecosystem services such as timber product outputs and carbon sequestration can be influenced by non-native plant invasions and present challenges to forest managers.

This project aims to provide a statewide assessment of the status and distribution of invasive plant species throughout New Hampshire that pose the greatest threat to forest systems. The project also will evaluate factors that increase forest resistance to colonization by invasive plants. Based on these factors, Gunn plans to provide management best practice guidelines to help foresters and landowners minimize the risk of invasive plant species invasion into native forest stands.

“There are a subset of invasive plants that can tolerate living in shaded conditions. This means they can persist under the canopy of native tree species that have important commercial value and are valuable in providing carbon storage and watershed protection services. If they persist, the invasive plants can change the forest in a way that could reduce the benefits we get from forests,” Gunn said.

“I’m interested developing some tools where landowners and foresters can evaluate the risk to their forest lands and then adjust the way they manage their forests to reduce the risk of invasion. The tools will include an online ‘web map’ where landowners can use their location and other information about their forest land to evaluate their risk of invasion by several non-native species,” he said.

According to Gunn, the suppression of commercial tree species regeneration and potential for reduced fitness and growth of resident plant species present challenges to forest managers and threatens New Hampshire’s $2.8 billion forest-based timber and recreation industry. In addition, by changing forest structure, hindering regeneration of long-lived species, and delaying stand development, other ecosystem services such as carbon sequestration in late-successional/old-growth forests and the protection of water quality in riparian forests also could be compromised by invasive species spread and colonization.

Gunn’s research project builds on the work of experiment station researcher Tom Lee, associate professor of natural resources and the environment, and other faculty funded by the experiment station. “My hope is to build on that work and integrate with my interests in the role that forests play in regulating climate through carbon sequestration and protecting water quality,” he said.

This material is based upon work supported by the NH Agricultural Experiment Station, through joint funding of the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 1010675, and the state of New Hampshire. Gunn is collaborating with Jeff Bowman at Trent University and the Ontario Ministry of Natural Resources and Jarlath O’Neil-Dunne at the UVM Spatial Analysis Lab, who will be conducting Unmanned Aerial System flights and analyzing the multi-spectral data collected during the flights.

Founded in 1887, the NH Agricultural Experiment Station at the UNH College of Life Sciences and Agriculture is UNH’s original research center and an elemental component of New Hampshire's land-grant university heritage and mission. We steward federal and state funding, including support from the USDA National Institute of Food and Agriculture, to provide unbiased and objective research concerning diverse aspects of sustainable agriculture and foods, aquaculture, forest management, and related wildlife, natural resources and rural community topics. We maintain the Woodman and Kingman agronomy and horticultural research farms, the Macfarlane Research Greenhouses, the Fairchild Dairy Teaching and Research Center, and the Organic Dairy Research Farm. Additional properties also provide forage, forests and woodlands in direct support to research, teaching, and outreach.